1. Field of the Invention
The present invention relates to a method used in a wireless communication system and related communication device, and more particularly, to a method of handling an interference measurement in a time-division duplexing (TDD) system and related communication device.
2. Description of the Prior Art
A long-term evolution (LTE) system supporting the 3rd Generation Partnership Project (3GPP) Rel-8 standard and/or the 3GPP Rel-9 standard are developed by the 3GPP as a successor of a universal mobile telecommunications system (UMTS), for further enhancing performance of the UMTS to satisfy increasing needs of users. The LTE system includes a new radio interface and a new radio network architecture that provides a high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes multiple evolved Node-Bs (eNBs) for communicating with multiple user equipments (UEs), and for communicating with a core network including a mobility management entity (MME), a serving gateway, etc., for Non-Access Stratum (NAS) control.
A LTE-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system. The LTE-A system targets faster switching between power states, improves performance at the coverage edge of an eNB, and includes advanced techniques, such as carrier aggregation (CA), coordinated multipoint (CoMP) transmission/reception, UL multiple-input multiple-output (MIMO), etc. For a UE and an eNB to communicate with each other in the LTE-A system, the UE and the eNB must support standards developed for the LTE-A system, such as the 3GPP Rel-10 standard or later versions.
Different from the LTE/LTE-A system operating in a frequency-division duplexing (FDD) mode, directions of subframes of a frequency band in the LTE/LTE-A system operating in a time-division duplexing (TDD) mode may be different. That is, the subframes in the same frequency band are divided into uplink (UL) subframes, downlink (DL) subframes and special subframes according to the UL/DL configuration specified in the 3GPP standard.
Please refer to FIG. 1 which is a table 10 of the UL/DL configuration with subframes and corresponding directions. In FIG. 1, 7 UL/DL configurations are shown, wherein each of the UL/DL configurations indicates a set of directions for 10 subframes, respectively. In detail, “U” means that the subframe is a UL subframe where UL data is transmitted, and “D” means that the subframe is a DL subframe where DL data is transmitted. “S” means that the subframe is a special subframe where control information and maybe data (according to the special subframe configuration) is transmitted.
However, eNBs in the LTE/LTE-A system operating in the TDD mode (hereinafter, the TDD system, for short) may be configured with various UL/DL configurations. In other words, a DL subframe for an eNB may be UL subframes for neighboring eNBs of the eNB, when the eNB and the neighboring eNBs are configured with different UL/DL configurations. Alternatively, a UL subframe for the eNB may be DL subframes for the neighboring eNBs of the eNB. In this situation, diverse measurement results may be obtained by the eNB or a UE in a coverage area of the eNB, when measurements of interferences are performed in different subframes. The diverse measurement results mainly come from that different combinations of subframe types of the eNB and the neighboring eNBs may occur in a single subframe. For example, a combination may be that a subframe is DL (or UL) for all of the eNB and the neighboring eNBs. In another example, a combination may be that a subframe is DL (or UL) for the eNB and some of the neighboring eNBs, while the subframe is UL (or DL) for the other neighboring eNBs. Thus, it is difficult for the eNB and the UE to utilize the diverse measurement results efficiently. Interference measurement in the TDD system becomes an important problem to be solved.